Exposure apparatus and exposure method

ABSTRACT

An exposure apparatus which projects a pattern of an original onto a substrate. The apparatus includes an original stage which supports the original, a substrate stage which supports the substrate, a reference pattern which is arranged on the original stage and to align the original stage and the substrate stage, and a mark, which is arranged on the original stage, has a known relative position from the reference pattern, and is to be projected onto the substrate to form an alignment mark on the substrate.

This application is a divisional application of copending U.S. patentapplication Ser. No. 10/784,256, filed Feb. 24, 2004.

FIELD OF THE INVENTION

The present invention relates to a technique for aligning a substrate.

BACKGROUND OF THE INVENTION

Semiconductors have recently been used not only for memories and CPUs,but also for CCDs and liquid crystal devices, and semiconductor exposureapparatuses have also been used to produce these devices. Video devicessuch as a CCD have color filters formed on chips for color display. Acolor filter is generally formed by applying a photoresist as a mixtureof R, G, and B coloring agents onto an entire wafer surface, and forminga color filter on CCD pixel cells by a photo process.

The arrangement and operation of a typical semiconductor exposureapparatus will be explained with reference to FIG. 7.

A wafer W to be exposed is set on a resist coating device COAT by atransport robot (not shown), or the like. The resist coating device COATapplies a resist REG into a thin film from a nozzle CN onto the wafer Wwhile rotating the wafer W. In order to strip the resist attached to theouter peripheral portion of the wafer W, the wafer W is transported to aresist rinsing device RINS. The resist rinsing mechanism is to spread aresist stripping solution RIN from the distal end of a nozzle RN andstrip the resist from the outer peripheral portion. This step isexecuted to prevent contamination of the lower surface of the wafer W atthe outer peripheral portion by the resist and contamination of the chipby stripping of the resist attached to the edge.

The wafer W is transported onto a wafer chuck CH on a two-dimensionallymovable wafer stage STG within the exposure apparatus. Intransportation, alignment measurement is executed to accurately measurethe wafer position on the wafer stage STG. In alignment measurement,alignment marks (e.g., PMR, PML, and FXY1 (FX1 and FY1) to FXY4 (FX4 andFY4) in FIG. 4) on the wafer W are measured using an alignment scope SCand image processing device P.

For coarse detection (pre-alignment), the scaling factor of thealignment socpe SC is set low to measure the positions of thepre-alignment marks PMR and PML. The purpose of the coarse detection isto measure an error left when the wafer W transported to the wafer chuckCH is set on the wafer chuck CH, and to reduce the error within thegrasp range of high-precision detection. Movement to the pre-alignmentmarks PMR and PML is done by moving the wafer stage STG. The wafer stageSTG is moved by a motor M in accordance with an instruction from acontrol device MC, while the position of the wafer stage STG isaccurately measured by a laser interferometer LP.

Light emitted by an alignment illumination device L1 illuminatespre-alignment marks PMOL and PMOR via a half-mirror M1. Light beamsreflected by the pre-alignment marks PML and PMR form images on aphotoelectric conversion element S1 such as a CCD camera via thehalf-mirror M1 and a half-mirror M2. Video signals from thephotoelectric conversion element S1 are converted into digital data byan analog/digital converter AD1. The digital data are stored in a memoryMEM1, and the positions of the marks are calculated by an imageprocessor COM1. The position of the wafer W is determined from the markpositions calculated by the image processor COM1 and a stage positiondesignated by the control device MC.

In order to measure a precise wafer position (high-precision alignment),the scaling factor of the alignment scope SC is set high to obtain thepositions of the high-precision alignment marks FXY1 to FXY4. Similar tocoarse detection, the stage position is moved to the high-precisionalignment mark FXY1, or the like. Light from the alignment illuminationdevice L1 irradiates the high-precision alignment mark FXY1, or thelike, and reflected light is received by a sensor S2. The sensor S2 alsoadopts a photoelectric conversion element such as a CCD or CCD camera.An electrical signal from the sensor S2 is converted into a digitalsignal by an analog/digital converter AD2. The digital signal is storedin a memory MEM2, and the mark position is calculated by an imageprocessor COM2. The mark positions of all the high-precision alignmentmarks FXY1 to FXY4 are determined by the same sequence, and the waferposition on the stage STG is accurately calculated.

After the end of alignment, the circuit pattern of a reticle R on areticle stage RSTG is projected onto the resist on the wafer W via aprojection lens LENS. In exposure, a masking blade MS is set inaccordance with an exposure region (PAT in FIG. 8) on the reticle R.Light emitted by an exposure illumination device IL exposes the wafer Wvia the masking blade MS, reticle R, and projection lens LENS.

When the wafer W is applied to production of a color CCD element, or thelike, the resist applied by the resist coating device COAT may result ina resist containing R, G and B coloring agents. In this case,illumination light may be absorbed in the resist in accordance with thewavelength of illumination light used in the alignment scope SC, failingto obtain a signal of a high-contrast alignment mark. As one solutionfor this problem, the wavelength of illumination light is changed to onewhich is not absorbed in the resist.

In this method, chromatic aberration of the alignment scope SC occurs.In a lens used for high-precision measurement, the wavelength width oflight for use must be limited to minimize aberration. It is, therefore,difficult to greatly change the wavelength for R, G, and B colors. Asanother solution method, a resist, which is applied onto an alignmentmark on a wafer and contains a coloring agent, is stripped.

To strip a resist from only the PMR portion and FXY1 portion in FIG. 4,the stripping solution must be applied to a narrow region (100 μm□),which is not practical. Considering this, there is proposed a method ofprinting an alignment pattern at the center peripheral portion of thewafer W, and stripping the resist using the resist rinsing device RINS(see, e.g., Japanese Patent Laid-Open Nos. 7-273018, 9-275058, and10-242043).

In recent years, the width of a scribe line for cutting an IC chip on acompleted wafer becomes narrower in order to maximize the area of thecircuit pattern. Demands have arisen for downsizing an alignment markprinted in a region such as a scribe line not serving as an IC chip.Depending on the step shape of the scribe line, it becomes difficult todetect an alignment mark due to distortion of an alignment mark signal.Under these circumstances, an alignment mark must be printed at aportion other than a scribe line.

When an exposure mark is formed at the end of a reticle in order toexpose a scribe line to an alignment mark, the mark may deform owing todistortion. The mark deformation generates a measurement error, and themark position, i.e., wafer position, cannot be accurately measured.

To print an alignment mark at the outer peripheral portion of a wafer,Japanese Patent Laid-Open Nos. 9-275058 and 10-242043 propose a methodof preparing exposure mark patterns PM and FM dedicated to alignmentmarks on the reticle R in addition to the circuit pattern PAT shown inFIG. 8. This method can also be applied when an alignment mark isprojected onto an arbitrary portion.

The flow of circuit pattern exposure and alignment mark exposure in theabove proposal will be roughly described.

Step 1: An exposure control program for exposure of a circuit pattern ona reticle is set.

Step 2: The masking blade is limited to the size of a circuit patternregion (PAT) on the reticle.

Step 3: The alignment mark of a wafer is measured to align the wafer andthe reticle.

Step 4: The wafer is exposed to the circuit pattern on the reticle.

Step 5: The program is changed to an exposure control program forexposure of an alignment mark pattern.

Step 6: The masking blade is limited to the region of a mark pattern (PMor FM) on the reticle.

Step 7: The wafer is exposed to the alignment mark.

This method has the following demerits (i) and (ii).

(i) This method requires two kinds of exposure control programs. For twoor more kinds of alignment marks, three or more kinds of exposurecontrol programs may be necessary.

(ii) Two regions, i.e., circuit and alignment mark regions, or moreregions must be ensured on a reticle.

Since the exposure apparatus must be controlled using a plurality ofexposure control programs, the program must be switched, decreasing theoperation speed of the exposure apparatus. Further, transfer of aprogram to a plurality of apparatuses in advance requires a largecapacity memory for storing the program. This requires an increase inresources for managing the semiconductor production exposure controlprograms and capacity of a storage device such as a disk.

When the exposure apparatus is so constituted as to project a patternwithin a fixed region on a reticle, no plurality of exposure controlprograms is required, but the limitations with respect to the circuitpattern area on the reticle increase. To prevent this, the exposureapparatus is arranged such that a circuit pattern and an alignment markpattern are prepared on a reticle only as needed so as to project thealignment mark to an arbitrary portion. In this case, theabove-mentioned problems arise.

SUMMARY OF THE INVENTION

It is an object of the present invention to solve the above-mentionedproblems (i) and (ii).

To solve the above-described problems and to achieve the object,according to the present invention, an exposure apparatus which projectsa pattern on an original onto a substrate comprises an original stagewhich supports the original, a substrate stage which supports thesubstrate, a reference pattern which is arranged on the original stageand to align the original stage and the substrate stage, and a markwhich is arranged on the original stage, has a known relative positionfrom the reference pattern, and is to be projected onto the substrate toform an alignment mark on the substrate.

According to the present invention, an exposure method of projecting apattern on an original onto a substrate comprises steps of measuring aposition of an alignment mark formed on the substrate, projecting thepattern onto the substrate based on a measurement result in themeasurement step, and projecting onto the substrate based on themeasurement result, a mark which has a known relative position from areference pattern arranged on an original stage and to align theoriginal stage and a substrate stage, and is arranged on the originalstage and to form an alignment mark on the substrate.

Other objects and advantages besides those discussed above shall beapparent to those skilled in the art from the description of a preferredembodiment of the invention, which follows. In the description,reference is made to the accompanying drawings, which form a partthereof, and which illustrate an example of the invention. Such anexample, however, is not exhaustive of the various embodiments of theinvention, and therefore reference is made to the claims, which followthe description for determining the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a semiconductor manufacturingapparatus according to an embodiment of the present invention;

FIG. 2 is a schematic view showing a reticle reference plate accordingto the embodiment of the present invention;

FIG. 3 is a schematic view showing a reticle stage and masking bladeaccording to the embodiment of the present invention;

FIG. 4 is a schematic view showing a wafer according to the firstembodiment;

FIGS. 5A to 5C are views showing the positional relationship between analignment mark and an exposure mark according to the embodiment of thepresent invention;

FIGS. 6A to 6C are schematic views showing a reticle reference plate andwafer according to the third embodiment;

FIG. 7 is a schematic view showing a conventional semiconductormanufacturing apparatus; and

FIG. 8 is a view showing a conventional reticle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments according to the present invention will bedescribed in detail below with reference to the accompanying drawings.

First Embodiment

FIG. 1 is a schematic view showing a semiconductor manufacturingapparatus according to the first embodiment of the present invention.FIG. 2 is a schematic view showing a reticle reference plate accordingto the first embodiment of the present invention. FIG. 3 is a viewschematically showing a reticle stage and masking blade according to theembodiment of the present invention.

In FIGS. 1 to 3, in the semiconductor exposure apparatus shown in FIG.1, a reticle reference plate PL is set on a reticle stage RSTG, whichholds a reticle R. The role of the reticle reference plate PL is tomeasure the positional relationship with a mark SLM (see FIGS. 5A to 5C)on a stage reference plate SL mounted on a two-dimensionally movablewafer stage STG. This determines the positional relationship between thereticle stage RSTG and the wafer stage STG. The stages RSTG and STG areso aligned as to set the positional relationship to zero. In this stage,a wafer W aligned by the following method is accurately exposed to apattern on the reticle R via a projection lens LENS. Note that even aconventional semiconductor manufacturing apparatus mounts a platecorresponding to the reticle reference plate PL.

The reticle reference plate PL has a pre-alignment mark PM andhigh-precision alignment mark FM shown in FIG. 2. As is apparent fromFIG. 1, light form an illumination light source EL can illuminate thewafer W via the reticle reference plate PL and projection lens LENS.When a mark pattern is formed on the reticle reference plate PL, it canbe projected onto the wafer W. The imaging plane of the reticlereference plate PL is identical to that of the reticle R. The image onthe reticle reference plate PL is accurately formed on the imaging planeof the projection lens, and an in-focus image is projected onto thewafer W. Hence, by forming an exposure alignment mark pattern on thereticle reference plate PL in advance, the alignment mark can beprojected onto the wafer W. The pattern on the reticle reference platePL is formed by etching a film of chromium, or the like.

The reticle reference plate PL has the mark PM for projectingpre-alignment marks PMOL and PMOR in FIG. 4, and the mark FM forprojecting high-precision alignment marks FXY01 to FXY04. In projectingthese marks, PM and FM cannot be simultaneously projected. Thus, amasking blade MS is so driven as to irradiate only the region of themark PM or FM on the reticle reference plate PL with exposure light.FIG. 3 is a view showing the reticle stage RSTG when viewed from thetop. FIG. 3 shows a state in which the masking blade MS is set so as toirradiate only the region of the mark FM with exposure light.

The mark PM or FM can be projected onto a designated position on thewafer W by setting the masking blade MS to the region of a mark to beprojected and moving the wafer stage STG to a position where the mark isto be projected. In this manner, the marks PMOL, PMOR, and FXY01 toFXY04 are projected onto an outer peripheral portion REGR of the waferW, as shown in FIG. 4.

The exposure flow of a series of operations from loading of the wafer Winto the exposure apparatus to unloading of the wafer W will beexplained with reference to FIGS. 1 to 4. For descriptive convenience,pre-alignment marks PML and PMR exist at an inner peripheral portionREGC (surface inward from the outer peripheral portion REGR) of thewafer W.

As shown in FIGS. 1 to 4, the wafer W is loaded into a resist coatingdevice COAT, coated with a resist REG, and then transferred onto a waferchuck CH mounted on the stage STG of the exposure apparatus. The twomarks PML and PMR of the wafer W on the wafer chuck CH are measured by alow-scaling-factor measurement method using an alignment scope SC. Bythis measurement, the positions X, Y and θ of the wafer W on the stageSTG are measured and corrected. High-precision alignment marks FXY1 toFXY4 are measured by a high-scaling-factor measurement method using thealignment scope SC. By this measurement, the position of the wafer W ismore accurately obtained, ending alignment measurement.

In low-scaling factor measurement, light emitted by an alignmentillumination device L1 illuminates the pre-alignment marks PML and PMRvia a half-mirror M1. Light beams reflected by the marks form images ona photoelectric conversion element S1, such as a CD camera, via thehalf-mirror M1 and a half-mirror M2. Video signals from thephotoelectric conversion element S1 are converted into digital data byan analog/digital converter AD1, and the digital data are stored in amemory MEM1. An image processor COM1 calculates the positions of themarks. The position of the wafer W is determined from the mark positionscalculated by the image processor COM1 and a stage position designatedby a control device MC.

In high-scaling-factor measurement, light emitted by the alignmentillumination device L1 irradiates the high-precision alignment markFXY1, or the like, and reflected light is received by a sensor S2. Thesensor S2 is also formed by a photoelectric conversion element such as aCCD camera. An electrical signal from the sensor S2 is converted into adigital signal by an analog/digital converter AD2, and the digitalsignal is stored in a memory MEM2. An image processor COM2 calculatesthe mark position.

The masking blade MS is so set as to expose the entire surface of thecircuit pattern on the reticle R. The pattern on the reticle R issequentially projected into regions S1, S2, S3, . . . , on the wafer Win accordance with the alignment measurement result.

The masking blade MS is set to the region of the mark PM (see FIGS. 2and 3). While the wafer stage STG is driven, the pattern PM is projectedonto the outer peripheral portion (positions of the marks PMOL and PMOR)of the wafer W. The masking blade MS is set to the region of the markFM. While the stage STG is driven, the pattern FM is projected onto theouter peripheral portion (positions of the marks FXY01 to FXY04) of thewafer W. Wafer exposure processing is then completed.

As described above, the alignment marks PM and FM are projected onto theouter peripheral portion of the wafer W by using alignment mark patternson the reticle reference plate PL. Unlike the prior art, no exposurecontrol program need be switched, and no pattern for projecting analignment mark onto the reticle R need be prepared. The exposureapparatus can project alignment marks onto the wafer W by using onlyexisting functions.

The resist of the formed wafer is developed, and an alignment mark isprinted at the outer peripheral portion of the wafer via an etchingprocess, or the like. The cleaned wafer from which the resist isstripped via the edging step, or the like, shifts to the next exposurestep. For example, the wafer is coated with a resist containing coloringagents for a color filter, and the resist is stripped from only theouter peripheral portion by a resist rinsing device. Since no resistexists in the alignment mark, the mark observed by the alignment scopedoes not exhibit any distortion or decrease in contrast caused by theresist. Accordingly, alignment can be executed at the highest precision.

The interrelationship among an exposure alignment mark on the reticlereference plate PL, an exposure alignment mark pattern, and waferalignment will be explained with reference to FIGS. 5A to 5C.

In FIGS. 5A to 5C, SPR represents the distance between a reticlereference mark RSM on the reticle reference plate PL. This distance ismeasured in advance. FZ represents the relative shift amount between thereticle reference mark RSM and a mark RM on the reticle, and is measuredin reticle alignment. PMZ represents the distance between the reticlestage reference mark PLM and the mark PM on the reticle reference platePL. Pattern data and data in drawing on the plate PL are measured inadvance. Similarly, FMZ represents the distance between the reticlestage reference mark PLM and the mark FM on the reticle reference platePL. Pattern data and data in drawing on the plate PL are measured inadvance.

When the circuit pattern of the reticle R is to be drawn at the lenscenter, the reticle stage RSTG is shifted by SPR-FZ by using the reticlestage reference mark PLM as the reference of the reticle stage RSTG, andthen exposure is done. Also, when the mark PM or FM is to be projected,the reticle stage RSTG is shifted by PMZ or FMZ to perform exposure, theshift amount from the lens center is reset to zero, and then exposure isdone (FIG. 5A).

On the wafer W, the wafer stage reference mark SLM on the stagereference plate SL is measured using the reticle stage reference markPLM as a reference. The stage reference plate SL is moved below thealignment scope SC to measure the same mark SLM. A baseline BL servingas the distance between the lens center and the alignment scope SC isobtained from the stage movement distance, the shift amount between themarks PLM and SLM, and the shift amount of the mark SLM on the alignmentscope SC (FIG. 5B).

In alignment of the wafer W, the alignment marks PML, PMR, and FXY1 toFXY4 on the wafer W are measured using the alignment scope SC, and thewafer center on the wafer stage STG is determined. Since the distance(baseline BL) between the lens center and the scope SC is measured inadvance, the wafer center on the stage STG is determined by measurementat the lens center by subtracting BL from a measurement value. Exposureis performed using the wafer center as a reference (FIG. 5C).

Movement in a direction (Y direction) parallel to the sheet surface inFIGS. 5A to 5C has been described. The above description can also beapplied to movement in a direction (X direction) perpendicular to thesheet surface. As for the wafer position on the wafer stage STG, notonly the X and Y positions, but also an amount (rotation component) bywhich the wafer W is rotated and mounted on the stage STG, and a waferexpansion/contraction amount (scaling component) are measured.

To expose each exposure shot on the wafer W to the pattern of thereticle R, the rotation component and scaling component are reflected inthe distance to a predetermined exposure shot, and the wafer stage STGis moved to the measured wafer center position reference. While theshift amount FZ from the reticle R is reflected in the reticle stageRSTG, the wafer W and reticle R are made to coincide with the center ofthe lens LENS. In this stage, exposure is performed. Exposure may becell exposure or scanning exposure.

Similarly, as for the marks PM and FM, the rotation component andscaling component are reflected in the distance to a predeterminedexposure position, and the wafer stage STG is moved to the measuredwafer center position reference. While the distance FMZ or PMZ isreflected in the reticle stage RSTG, the wafer W and the exposure markare made to coincide with the center of the lens LENS. In this state,exposure is performed. Exposure may be cell exposure or scanningexposure.

In this way, both the exposure pattern of the reticle R and thealignment mark pattern on the reticle reference plate PL are aligned tothe layout on the wafer W, and projected onto the wafer W. Alignment isexecuted using these projected alignment marks in subsequent steps, andaccurate alignment corresponding to the layout on the wafer can beachieved.

The first embodiment has exemplified an exposure apparatus (scanningexposure apparatus, or the like) in which the reticle stage RSTG ismovable. Even in an exposure apparatus in which the reticle stage RSTGis fixed, the same alignment mark exposure as that in the firstembodiment can be realized by the arrangement of the masking blade andmovement of the wafer stage as far as the alignment mark falls outsidethe reticle region and within the projectable region of the projectionlens.

Also, in an electron beam exposure apparatus, the alignment mark can beprojected onto an arbitrary portion by an electron beam via movement ofthe wafer stage.

Second Embodiment

The first embodiment has described a method of stripping the resist REGto expose an alignment mark. When the transmittance of the resist REG ishigh, no resist REG need be stripped. The second embodiment is the sameas the first embodiment in exposure of an alignment mark except that noresist REG is stripped. The characteristic feature of this method isthat an alignment mark printed on a conventional scribe line can beprojected onto an arbitrary portion on a wafer. For example, analignment mark is projected onto a peripheral wafer region where no chipcan be formed. In general, the semiconductor chip is rectangular, butthe wafer is circular. This produces a plurality of fan-shaped regionswhere no chip can be formed. Alignment marks are projected ontoarbitrary portions in the fan-shaped regions. FIGS. 6B and 6C show anexample in which alignment marks are arranged in fan-shaped regionsformed at four corners owing to the layout.

The second embodiment has also exemplified an exposure apparatus inwhich the reticle stage is movable. Even in an exposure apparatus inwhich a reticle stage RSTG is fixed, the same alignment mark exposure asthat in the second embodiment can be realized by the arrangement of themasking blade and movement of the wafer stage as far as the alignmentmark falls outside the reticle region and within the projectable regionof the projection lens.

Also, in an electron beam exposure apparatus, the alignment mark can beprojected onto an arbitrary portion by an electron beam via movement ofthe wafer stage.

Third Embodiment

In the above-described embodiments, an alignment mark to be projectedcan be formed at an arbitrary portion on a wafer. When an alignment markis projected onto a portion near the alignment mark of a precedinglayer, the similar alignment marks are arranged adjacent to each other.In alignment mark measurement, a mark other than a target may bedetected. This results in a measurement error, and no accurate waferposition can be obtained. To identify an exposed alignment mark,different marks are used such that the shape or size is changed orauxiliary patterns with different shapes are added. As shown in FIG. 6A,various marks are prepared as the marks PM and FM. For example, PM2 isarranged as a size change (reduction) example of PM1, and FM1, FM2, FM3,FM4, and FM5 prepared by adding different identification marks to FM arearranged. The identification mark and mark deformation example are notlimited to the types shown in FIG. 6A as far as a mark can be detected.

Also, when four alignment marks FXY11, FXY21, FXY31, and FXY41 areprinted in fan-shaped regions shown in FIG. 6B, these marks are formedas alignment marks each having one of four different types ofidentification marks FM1, FM2, FM3, and FM4. For example, when the shapeof mark FM1 represents a target alignment mark, a square identificationmark is added to the upper left portion of the mark. An image processingdevice P recognizes the mark on the basis of this mark type information.

In exposure control, the following settings are done.

(1) Setting of an exposure control program (alignment mark coordinates,the shape (mark type) of the identification mark, the layout, and thelike).

(2) Alignment mark printing control information (control information onwhether to print a new alignment mark or not, the shape (type) of analignment mark to be newly printed, the coordinates of an alignment markto be newly printed, and the like).

An alignment mark on the wafer that is designated by these settings isidentified and detected. The wafer position is accurately measured, andthe pattern on the reticle is projected. The masking blade is adjustedto a designated alignment mark, and the alignment mark is projected atdesignated coordinates. An alignment mark to be newly printed isprojected onto a designated position on the wafer whose position hasaccurately been measured. Thus, the alignment mark is accurately alignedto the layout.

In a detailed exposure control program, for example, PM1 and FM1 are setas identification mark shapes. As shown in FIG. 6B, the positions ofmarks PMOL and PMOR are measured using PM1 to measure rough X, Y, and θpositions. FXY11, FXY12, FXY13, and FXY14 are measured using FM1.Control information on printing an alignment mark represents that FM5 isused as a new alignment mark and is to be printed at four predeterminedportions on the wafer.

As for identification of an auxiliary pattern, the presence/absence ofan identification mark is determined using the low-scaling-factordetection system of the alignment scope after template matching of themark. If no identification mark is detected, an erroneous mark existsbelow the scope, and whether a correct mark exists within the field ofview is detected. If a correct mark exists, the stage is moved to theposition of the mark to calculate the accurate position of the markusing the high-scaling-factor system. Instead of separately determiningan identification mark, the template may have an identification mark, ora template which detects a mark in a different shape may be adopted.

Even if no target mark is found in adjacent marks, the stage can bemoved to the target mark because the relative distance to the targetmark has been known. More specifically, even when not all the four marksshown in FIG. 6C fall within the field of view of the low-scaling-factorsystem and the target mark FXY11 does not fall within the field of view,the position of FXY11 can be confirmed from the known relative distancebetween FXY11 and FXY41 as far as FXY41 exists within the field of viewand can be detected. The positions and shapes (types) of marks whichhave been printed are stored as a log in the exposure control program.

If the relative distance to a target mark is known, the target markposition can also be calculated from a detected mark position and theknown relative distance without moving the stage to the target mark.

In this manner, even when alignment marks are sequentially printed in anarrow region, erroneous mark recognition can be suppressed without anyrestrictions by a scribe line.

Alternatively, at least one designated type of pattern out of aplurality of alignment mark patterns of different shapes (types) on areticle may be projected onto a wafer.

The third embodiment has also exemplified an exposure apparatus in whichthe reticle stage is movable. Even in an exposure apparatus in which areticle stage RSTG is fixed, the same alignment mark exposure as that inthe third embodiment can be executed by the arrangement of the maskingblade and movement of the wafer stage as far as the alignment mark fallsoutside the reticle region and within the projectable region of theprojection lens. In addition, adjacent marks can be identified. Theseeffects can also be attained in an electron beam exposure apparatus.

According to the above-described embodiments, an alignment mark can beprinted at the outer peripheral portion of a wafer using functionsmounted in advance in a semiconductor manufacturing apparatus. A programfor controlling an exposure apparatus can be specialized only inexposure of a reticle pattern. This makes the exposure apparatus moreconvenient without decreasing the operation speed of the apparatus.

No region dedicated to an alignment mark need be prepared on a reticle,and the reticle area can be utilized best. According to this method, analignment mark can be easily printed at the outer peripheral portion ofthe wafer using the resist rinsing function, exposing the alignmentmark. A shift of a measurement value by the resist, or the like, can bereduced in alignment mark measurement, which increases the semiconductormanufacturing yield.

The method of printing an alignment mark in a blank region on a waferother than a scribe line is free from any restriction of utilizing afinite resource such as the length and width of a scribe line. The typeand size of a mark, and the distance from an adjacent pattern can be setadvantageously to alignment. This also contributes to an increase insemiconductor manufacturing yield.

The position of an alignment mark to be projected can be arranged at thecentral optical axis of the projection lens to optimize the imageperformance of the alignment mark to be projected. In this case, themark does not deform under the influence of distortion, and an accuratemark position can be calculated to accurately obtain the wafer positionon the wafer stage. As a result, the alignment performance is improved,contributing to the semiconductor manufacturing yield.

The identification method adopted when many alignment marks are printedadjacent to each other can prevent erroneous detection of an alignmentmark printed in another step, and reduce the area necessary for analignment mark.

Other Embodiment

The functions of the above-described embodiments are also achieved whensoftware, such as a program for realizing the pattern exposure flow ofthe embodiments, is supplied to a system or apparatus directly or from aremote place, and the computer of the system or apparatus reads out andexecutes the supplied software. In this case, the software need not be aprogram as far as the software has a program function.

Hence, the embodiments of the present invention include software itselfwhich is installed in a computer in order to realize the function orprocessing of the above-described embodiments.

In this case, the software includes an object code, a program executedby an interpreter, script data supplied to an operating system (OS), andthe like. The type of software is not particularly limited.

The recording medium for supplying the software includes, e.g., aflexible disk, a hard disk, an optical disk, a magnetooptical disk, anMO, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM,and a DVD (DVD ROM or DVD R).

The software can also be supplied by downloading the software itself ora compressed file containing an automatic installing function from anInternet homepage to a recording medium such as a hard disk by using thebrowser of a client computer. The software can also be supplied bydividing it into a plurality of files and downloading the files fromdifferent homepages. Hence, the embodiments of the present inventionalso include a World Wide Web (WWW) server, which allows the user todownload the software.

The software can also be supplied by distributing to the user a storagemedium, such as a CD-ROM, which stores the encrypted software, causing auser who satisfies predetermined conditions to download decryption keyinformation from a homepage via the Internet, and installing in acomputer the encrypted software by using the key information.

The functions of the above-described embodiments are realized byexecuting the readout software by a computer. The embodiments of thepresent invention also include a case in which an OS, or the like,running on the computer performs part of or all of actual processing onthe basis of the instructions of the software, and this processingrealizes the functions of the above-described embodiment.

Further, the embodiments of the present invention include a case inwhich, after the software read out from the recording medium is writtenin the memory of a function expansion board inserted into the computeror the memory of a function expansion unit connected to the computer,the CPU of the function expansion board or function expansion unitperforms part of or all of actual processing on the basis of theinstructions of the software, and this processing realizes the functionsof the above-described embodiments.

As many apparently widely different embodiments of the present inventioncan be made without departing from the spirit and scope thereof, it isto be understood that the invention is not limited to the specificembodiments thereof except as defined in the appended claims.

1-20. (canceled)
 21. An exposure apparatus for exposing a substrate tolight directed via an original, said apparatus comprising: an originalstage configured to hold the original and to move; a substrate stageconfigured to hold the substrate and to move; a reference mark arrangedon said original stage and configured so that a positional relationshipbetween said original stage and said substrate stage is measured; analignment mark pattern arranged on said original stage and configured tobe imaged on the substrate to form an alignment mark on the substrate,said alignment mark pattern having a known position relative to saidreference mark; and a projection optical system configured to directlight from a selected one of a pattern of the original and saidalignment mark pattern, and to image the selected one on the substrate.22. An apparatus according to claim 21, further comprising: an alignmentscope configured to detect the alignment mark formed on the substrate; aprocessor configured to obtain a position of the alignment mark based ona detection by said alignment scope; and a controller configured tocontrol a position of said substrate stage based on a position of thealignment mark obtained by said processor.
 23. An apparatus according toclaim 21, wherein said controller is configured to control a position ofsaid original stage and a position of said substrate stage so that saidalignment mark pattern is imaged in a peripheral region of the substrateoutside a region where the pattern of the original is to be imaged. 24.An apparatus according to claim 21, wherein a plurality of saidalignment mark patterns of which kinds are different from each other arearranged on said original stage.
 25. An apparatus according to claim 24,wherein said alignment mark pattern comprises an identification patternfor identifying the kind.
 26. An apparatus according to claim 25,further comprising: an alignment scope configured to detect thealignment mark formed on the substrate; a processor configured to obtainthe kind and a position of the alignment mark based on a detection bysaid alignment scope; and a controller configured to control a positionof said substrate stage based on the kind and a position of thealignment mark obtained by said processor.
 27. An apparatus according toclaim 26, wherein said controller is configured to control a position ofsaid substrate stage so that said alignment scope detects the alignmentmark of which the kind is a first kind, based on a position of thealignment mark of which the kind is a second kind, different from thefirst kind, obtained by said processor.
 28. An apparatus according toclaim 21, wherein said reference mark and said alignment mark patternare arranged on a plate which is arranged on said original stage.
 29. Amethod of manufacturing a device, said method comprising steps of:exposing a substrate to light directed via an original using an exposureapparatus as defined in claim 21; developing the exposed substrate; andprocessing the developed substrate to manufacture the device.
 30. Anexposure method of exposing a substrate to light directed via anoriginal, said method comprising steps of: measuring a positionalrelationship between an original stage, configured to hold the originaland to move, and a substrate stage, configured to hold the substrate andto move, using a reference mark arranged on the original stage; imaginga pattern of the original held by the original stage on the substrateheld by the substrate stage using a projection optical system configuredto direct light from the original based on the positional relationship;and imaging an alignment mark pattern arranged on the original stage onthe substrate held by the substrate stage using the projection opticalsystem based on the positional relationship to form an alignment mark onthe substrate, the alignment mark pattern having a known positionrelative to the reference mark.